diff --git a/tools/testing/kunit/kunit_tool_test.py b/tools/testing/kunit/kunit_tool_test.py
index 5bb7b118ebd9..f0da3f565577 100755
--- a/tools/testing/kunit/kunit_tool_test.py
+++ b/tools/testing/kunit/kunit_tool_test.py
@@ -247,14 +247,14 @@ class KUnitMainTest(unittest.TestCase):
 	def test_build_passes_args_pass(self):
 		kunit.main(['build'], self.linux_source_mock)
 		assert self.linux_source_mock.build_reconfig.call_count == 0
-		self.linux_source_mock.build_um_kernel.assert_called_once_with(False, 8, '', None)
+		self.linux_source_mock.build_um_kernel.assert_called_once_with(False, 8, '.kunit', None)
 		assert self.linux_source_mock.run_kernel.call_count == 0
 
 	def test_exec_passes_args_pass(self):
 		kunit.main(['exec'], self.linux_source_mock)
 		assert self.linux_source_mock.build_reconfig.call_count == 0
 		assert self.linux_source_mock.run_kernel.call_count == 1
-		self.linux_source_mock.run_kernel.assert_called_once_with(build_dir='', timeout=300)
+		self.linux_source_mock.run_kernel.assert_called_once_with(build_dir='.kunit', timeout=300)
 		self.print_mock.assert_any_call(StrContains('Testing complete.'))
 
 	def test_run_passes_args_pass(self):
@@ -262,7 +262,7 @@ class KUnitMainTest(unittest.TestCase):
 		assert self.linux_source_mock.build_reconfig.call_count == 1
 		assert self.linux_source_mock.run_kernel.call_count == 1
 		self.linux_source_mock.run_kernel.assert_called_once_with(
-			build_dir='', timeout=300)
+			build_dir='.kunit', timeout=300)
 		self.print_mock.assert_any_call(StrContains('Testing complete.'))
 
 	def test_exec_passes_args_fail(self):
@@ -302,7 +302,7 @@ class KUnitMainTest(unittest.TestCase):
 	def test_exec_timeout(self):
 		timeout = 3453
 		kunit.main(['exec', '--timeout', str(timeout)], self.linux_source_mock)
-		self.linux_source_mock.run_kernel.assert_called_once_with(build_dir='', timeout=timeout)
+		self.linux_source_mock.run_kernel.assert_called_once_with(build_dir='.kunit', timeout=timeout)
 		self.print_mock.assert_any_call(StrContains('Testing complete.'))
 
 	def test_run_timeout(self):
@@ -310,7 +310,7 @@ class KUnitMainTest(unittest.TestCase):
 		kunit.main(['run', '--timeout', str(timeout)], self.linux_source_mock)
 		assert self.linux_source_mock.build_reconfig.call_count == 1
 		self.linux_source_mock.run_kernel.assert_called_once_with(
-			build_dir='', timeout=timeout)
+			build_dir='.kunit', timeout=timeout)
 		self.print_mock.assert_any_call(StrContains('Testing complete.'))
 
 	def test_run_builddir(self):